Acne is a common human skin disease, which is characterized by areas of skin with seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules) and possibly scarring. Acne affects mostly skin with the densest population of sebaceous follicles. These areas include face, upper part of chest and the back. Severe acne is inflammatory, but acne can also manifest in non-inflammatory forms.
Acne occurs most commonly during adolescence and affects more than 96% of teenagers which often continues into adulthood. In adolescence, acne is usually caused by an increase in male sex hormones, which people of both genders accrue during puberty.
Acne scars are the result of inflammation within the dermis brought on by acne. The scar is created by the wound trying to heal itself resulting in too much collagen in one spot. Physical acne scars are often referred to as “Icepick” scars. This is because the scars tend to cause an indentation in the skin's surface.
Pigmented scars are usually the result of nodular or cystic acne (the painful ‘bumps’ lying under the skin). They often leave behind an inflamed red mark. Often, the pigmentation scars can be avoided simply by avoiding aggravation of the nodule or cyst. When sufferers try to ‘pop’ cysts or nodules, pigmentation scarring becomes significantly worse and may even bruise the affected area. Pigmentation scars nearly always fade with time taking between three months to two years to do so, however it can also persist.
Causes of Acne:
Acne develops as a result of blockages in follicles. Hyperkeratinization and formation of a plug of keratin and sebum (a microcomedo) is the earliest change. Enlargement of sebaceous glands and an increase in sebum production occur with increased androgen (DHEA-S) production at adrenarche. The microcomedo may enlarge to form an open comedone (blackhead) or closed comedone (milia). Comedones are the direct result of sebaceous glands' becoming clogged with sebum, a naturally occurring oil and dead skin cells. In these conditions, the naturally occurring largely commensal bacterium Propionibacterium acnes can cause inflammation, leading to inflammatory lesions (papules, infected pustules, or nodules) in the dermis around the microcomedo or comedone which results in redness and may result in scarring or hyperpigmentation.
Hormonal
Hormonal activity, such as menstrual cycles and puberty, may contribute to, the formation of acne. During puberty, an increase in male sex hormones called androgens causes the follicular glands to grow larger and make more sebum. Use of anabolic steroids may have a similar effect. Several hormones have been linked to acne: the androgens testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone sulfate (DHEAS), as well as insulin-like growth factor 1 (IGF-I).
Development of acne vulgaris in later years is uncommon, although this is the age group for rosacea, which may have similar appearances. True acne vulgaris in adult women may be a feature of an underlying condition such as pregnancy and disorders such as polycystic ovary syndrome or the rare Cushing's syndrome. Menopause-associated acne occurs as production of the natural anti-acne ovarian hormone estradiol fails at menopause. The lack of estradiol also causes thinning hair, hot flashes, thin skin, wrinkles, vaginal dryness, and predisposes to osteopenia and osteoporosis as well as triggering acne.
Genetic
The tendency to develop acne runs in families. For example, school aged boys with acne often have other members in their family with acne, as well. A family history of acne is associated with an earlier occurrence of acne and an increased number of retentional acne lesions.
Psychological
While the connection between acne and stress has been debated, scientific research indicates that “increased acne severity” is “significantly associated with increased stress levels. The National Institutes of Health (USA) list stress as a factor that “can cause an acne flare.
Infectious
Propionibacterium acnes (P. acnes) is the anaerobic bacterium which may be involved in formation of acne.
Diet
A high glycemic load diet and cow's milk have been associated with worsening acne.